Preparation and derivatives of poly-(6-O-methacryloyl-D-galactose) and poly-(6-O-acryloyl-D-galactose)
The 6-methacryloyl and 6-acryloyl esters of 1,2:3,4-di-O-isopropylidene-α-D-galactopyranose have been synthesised and polymerised to polymers of high molecular weight. The isopropylidene blocking groups have been removed by treatment with formic acid–water at 20°, to give poly-(6-O-methacryloyl-D-galactose) and poly-(6-O-acryloyl-D-galactose); which are linear, water-soluble, and reducing polymers with novel properties not possessed by natural polysaccharides. Various derivatives of these polymers are described. Chlorous acid at pH 3 oxidises the reducing group at C-1 of these polymers to give poly-(6-O-methacryloyl-D-galactonic acid) and poly-(6-O-acryloyl-D-galactonic acid), which exist in solution only; isolation and drying leads to loss of water from each galactonic acid residue with formation of the poly-1,4-lactones. The sodium salts of these polyacids are viscous polyelectrolytes which precipitate in the presence of many metal ions.